Title of Invention

PROGRESSIVE ADDITION LENSES WITH VARYING POWER PROFILES

Abstract A spectacle tens comprising a first surface having a first channel and a first channel power profile and a second surface having a second channel and a second channel power profile, wherein the channel power profile of the lens is the vector sum of the channel power profiles.
Full Text PROGRESSIVE ADDITION LENSES WITH VARYING POWER PROFILES
Field of the Invention
The present invention relates to multifocal ophthalmic lenses. In particular,
the invention provides lenses in which the channel power progression is customized
to the wearer's viewing posture.
Background of the Invention
The use of ophthalmic lenses for the correction of ametropia is well known.
For example, multifocal lenses, such as progressive addition lenses ("PALs"), are
used for the treatment of presbyopia. Typically, a PAL provides distance,
intermediate, and near vision zones in a gradual, continuous progression of
increasing dioptric power. PALs are appealing to the wearer because the lenses are
free of the visible ledges between the zones of differing optical power that are found
in other types of multifocal lenses, such as bifocals and trifocals.
As the wearer's eyes move from the distance, through the intermediate, and
into the near vision zones of a PAL, the wearer's eyes converge bringing the pupils
closer together. Ideally, the design of a PAL would be such that the power
progression from the distance zone, through the intermediate and to the near zone
matches the wearer's requirements as the eye scans the lens. However, in the design
of conventional PAL's, a trade-off is made between the power progression
distribution and the level of unwanted astigmatism of the lens.
Unwanted astigmatism is astigmatism introduced or caused by one or more
of the lens surfaces resulting in image blurring, distorting, and shifting for the lens
wearer. In order to reduce unwanted astigmatism, the power progression is
distributed over a greater length in some designs. Due to this lengthened
distribution, the power distribution may not meet the wearer's requirements and the
wearer may have to alter their natural viewing posture, or head and eye position, in
order to use the intermediate and near vision zones of the lens. In those lens designs

in which the power progression distribution is over a shorter length, a more natural
viewing posture may be provided, but the level of unwanted astigmatism is
increased reducing the useable area of the lens.
Thus, a need exists for a PAL that provides a power progression distribution
tailored to the requirements of the wearer's natural eye path, but that does not
increase the lens' unwanted astigmatism. Additionally, a need exists for a method to
determine the preferred viewing posture of the wearer so that the wearer is not
required to make significant viewing posture adaptations to use the lens.
Brief Description of the Drawings
FIG. 1 is a diagrammatic representation of the lens channel power profiles of
the lenses of Examples 2, 3 and 4.
FIG. 2 is a diagrammatic representation of the surface channel power profiles
of the lenses of Examples 2, 3, and 4.
FIG. 3 is a diagrammatic representation of the surface channel power profiles
of the lenses of Examples 5 and 6.
FIG. 4 is a diagrammatic representation of the lens channel power profiles of
the lenses of Examples 5 and 6.
FIG. 5 is a diagrammatic representation of the lens channel power profile of
the lens of Example 7.
FIG. 6 is a diagrammatic representation of the surface channel power profile
of the lens of Example 7.
Description of the Invention and its Preferred Embodiments
The present invention provides lenses, as well as methods for their design
and production, in which the power distribution between the distance and near vision
zone substantially meets the requirements of the wearer's eye path and refractive

power. This power distribution is obtained without reducing the useable lens surface
by introducing additional unwanted astigmatism.
In one embodiment, the invention provides a lens comprising, consisting
essentially of, and consisting of a first surface having a first channel and a first
channel power profile and a second surface having a second channel and a second
channel power profile, wherein the channel power profile of the lens is the vector
sum of the channel power profiles. By "lens" is meant any ophthalmic lens
including, without limitation, spectacle lenses, contact lenses, intraocular lenses and
the like. Preferably, the lens of the invention is a spectacle lens.
The surfaces used in the lens of the invention may be progressive addition
surfaces or regressive surfaces. By "progressive addition surface" is meant a
continuous, aspheric surface having distance and near viewing or vision zones, and a
zone of increasing dioptric power connecting the distance and near zones. By
"regressive surface" is meant a continuous, aspheric surface having zones for
distance and near viewing or vision, and a zone of decreasing dioptric power
connecting the distance and near zones. By "channel" is meant the corridor of
vision that is free of unwanted astigmatism of about 0.75 diopters or greater when
the wearer's eye is scanning through the intermediate vision zone to the near vision
zone and back. By "channel power profile" or 'power profile" is meant the power
distribution along the channel length. By "channel length" is meant the distance
from the lens' fitting point to a point along the channel at which the dioptric add
power is about 85 percent of the dioptric add power of the surface. By "fitting
point" is meant the point on a lens aligned with the wearer's pupil in its distance
viewing position when the wearer is looking straight ahead. By "dioptric add
power" is meant the amount of dioptric power difference between the near and far
vision zones of a lens or surface.

It is one discovery of the invention that a channel power profile suited to a
specific lens wearer's requirements may be achieved by using at least two surfaces,
each having a channel power profile. The channel power profiles may be
substantially the same or different. The channels of the surfaces may be aligned or
displaced. By aligned is meant that the major reference point of one channel is
superposed on that of the other channel. By "major reference point" is meant the
point of intersection of the primary meridian with the beginning of the channel, x =
0, y = 0. By displaced is meant that major reference point of one channel is
displaced downwardly with respect to that of the other channel. Either embodiment
permits a large range of channel power profiles while limiting the number of
surfaces required.
In general, the channel power profile, P(x,y), of a progressive lens may be
calculated as a vector sum of the profiles of each surface of the lens. For example,
for a lens with two progressive surfaces, S' and S", which surfaces have channel
power profiles P'(x,y) and P"(x,y), respectively, the power profile for the lens may
be calculated according to the following equation:
P(x,y) = P'(x,y) + P"(x-dx,y-dy) (1)
wherein dx and dy are the x and y components of the displacement of the fitting
point of surface S" with respect to surface S'.
For example, S' may be a convex progressive surface and S" a concave
progressive surface. Surface S" may be displaced vertically downwards relative to
S' by a distance dy. If L' is the channel length of surface S', L" is the channel length
of the surface S", and L" > L', then the channel length L of the lens formed by
combining surfaces S' and S" is calculated as L = L" + dy. The channel power
profile will change in accordance with equation 1. If, however, L" displacement of S" downwards relative to S' will not change the channel length of

the lens which will remain L = L', but will change the channel power profile within
the channel. In the case in which surfaces S' and S" are not displaced, or in which
dx = dy = 0, the channel length L is the greater of L' and L" and the power profile
will change to be a vector sum according to equation 1.
Thus, either or both the channel power profiles of the individual surfaces and
displacement distances may be selected so that one can independently customize the
channel power profile for a particular wearer. Either or both the channel profile
difference and displacement will also misalign the areas of maximum unwanted
astigmatism of the surfaces and the overall maximum astigmatism of the lens will be
lower than the sum of the individual surfaces.
Preferably, two progressive surfaces, one concave and one convex surface,
with the same or similar channel power profiles are used and the varying channel
power profile of the lens is obtained by displacement. The displacement of the
surfaces' channels must be done in a manner so that either or, preferably both, the
channels' centerlines and the channels' lateral edges' alignment is maintained. In
this way, introduction of an unacceptable level of distortion in the channel may be
avoided. Further, the displacement must be carried out so that unacceptable prism
power, which may act to disrupt the wearer's vision, is not introduced. More
preferably, the displacement is along the centerlines of the surfaces' channels with
maintenance of the centerlines' alignment. The displacement may be about 0.1 mm
to about 20 mm, preferably about 1 mm to about 10 mm, more preferably about 2
nun to about 7 nan.
In another embodiment, the invention provides a method for producing a lens
comprising, consisting essentially of, and consisting of the steps of: a.) measuring a
lens wearer's eye path and refractive power requirement while the wearer is viewing
an object at a distance, an intermediate, and a near position; and b.) providing a lens

with a channel power profile based on the lens wearer's eye path and refractive
requirement. By "eye path" is meant the course over a progressive or regressive
surface that is aligned with the lens wearer's pupil as the eye scans from the fitting
point to the wearer's natural near vision position.
In the method of the invention, the channel power profile for the lens wearer
is obtained by determining the wearer's eye path and the refractive power required
by the wearer along that eye path. The eye path may be determined by any known
technique. For example, the wearer may be provided with one or more lenses. The
wearer then views at least three objects at distance, intermediate, and near locations
while maintaining a natural viewing posture. It will be recognized that the more
measurements made along the eye path, the greater the accuracy of the power profile
obtained will be. Thus, preferably at least three points are measured along the eye
path. The pupil position of the eye is recorded, for example by marking the lens
surface, along the eye path. Conventional eye charts or fixation targets may be used
to ensure that a stable pupil position is maintained during the measurement.
The refractive power required by the wearer at each of the measured
locations may be determined by using techniques well known in the an including,
without limitation, the use of trial lenses or a phoropter. The channel power profile
required by the wearer is then calculated from the refractive power measurements at
each position along the eye path. One convenient method that may be used is to
graphically connect the refractive power measurements by a smooth curve when
plotted as a function of length below the fitting point One ordinarily skilled in the
art will recognize that any of a variety of other methods may be used, such as fitting
using the best equation through the measurements, all of which are within the scope
of the invention. The eye path measurements for a lens wearer preferably is
conducted separately for each eye because each of the wearer's eyes usually has a
unique eye path.

The lenses and methods of the invention may be used to provide a variety of
power profiles for one lens wearer, each suited to a specific task to be carried out by
the wearer. For example, displacement may increase the channel profile length so
that a power plateau for intermediate distance tasks is provided. Alternatively, the
profile may be shortened to provide an elongated near vision zone for reading.
The progressive or regressive surfaces used in the lenses of the invention
may be designed and optimized by any known method including, without limitation,
the use of commercially available design software. The surfaces may be on a
convex surface, a concave surface, a surface intermediate the concave and convex
surface, or combinations thereof. One ordinarily skilled in the art will recognize
that, if a progressive surface forms the convex surface of the lens, the distance vision
zone curvature will be less than that of the near zone curvature. Conversely, if the
progressive surface is the lens' concave surface, the distance curvature will be
greater than that of the near zone.
The channel power profile for each surface may be selected from any of the
known power profiles including, without limitation, linear, spline, trigonometric,
and the like. The channel power profile for each surface may be the same or
different. In all cases, the channel power profile resulting for the lens must
substantially meet the wearer's eye path and refractive requirements when the
wearer is maintaining a natural viewing posture.
If surfaces are used in which the power progression decreases from the far
vision to the near vision zone, the dioptric add power of the surface will be less than
zero. The dioptric add power of each of the surface used in the invention is selected
so that, when the surfaces are combined into a lens, the add power of the lens will
equal that needed to correct the lens wearer's near vision acuity.

The dioptric add power of each surface used in the invention may
individually be about -3.00 to about +6.00 diopters, preferably about -2.00 diopters
to about +5.00 diopters, more preferably about -1.00 to about +4.00 diopters. The
surfaces each may contain spherical power, cylinder power and axis, or
combinations thereof.
The lenses of the invention may be fabricated by any convenient means and
constructed of any known material suitable for production of ophthalmic lenses.
Suitable materials include, without limitation, polycarbonate, allyl diglycol,
polymethacrylate, and the like. Such materials are either commercially available or
methods for their production are known. Further, the lenses may be produced by
any conventional lens fabrication technique including, without limitation grinding,
whole lens casting, molding, thermoforming, laminating, surface casting, or
combinations thereof. Casting may be carried out by any means, but preferably is
performed by surface casting including, without limitation, as disclosed in United
States Patent Nos. 5,147,585, 5,178,800, 5,219,497, 5,316,702, 5,358,672,
5,480,600, 5,512,371, 5,531,940, 5,702,819, and 5,793,465 incorporated herein in
their entireties by reference.
The invention will be clarified further by the following, non-limiting
examples.
Examples
Example 1
A lens wearer's pupil positions are photographed while the wearer is viewing
objects at distance, intermediate, and near positions. The wearer wears single vision
lenses for distance and intermediate vision and reading lenses for near vision. For
distance viewing, a Snellen eye chart is placed 3 m from the wearer's pupils and for
intermediate viewing, the chart is placed on a table that is 64 mm from the pupils.
For near vision, the wearer is placed approximately at the wearer's natural reading

position, which for the wearer of Example 1 is approximately 40 mm from the
pupils. The wearer is found to require 0.00, 1.00, and 2.00 diopters sphere power for
the distance, intermediate, and near vision, respectively. The pupil positions, as
projected on the convex surface of the lens, for intermediate and near viewing are
found to be 8.5 mm and 17.5 mm vertically below the pupil position during distance
viewing, respectively Thus, the point at which the lens wearer will require the center
of the near vision zone to be located is approximately 4 mm below the channel end,
making the channel length 17.5 mm - 4.0 mm = 13.5 mm.
Example 2
Convex and concave progressive surfaces are provided. The convex surface
has a distance curvature of 6.00 diopters and near zone curvature of 7.00 diopters.
The channel power profile of the convex surface is shown in FIG. 2 as convex profile
A. The channel length of this surface is 11 mm. The concave surface has a distance
zone curvature of 6.00 diopters and a near zone curvature of 5.00 diopters. The
channel power profile for the concave surface is shown in FIG. 2 as concave profile
C and the channel length is 13 mm. The concave surface channel's major reference
point is displaced downward 2 mm relative to the convex surface optical center. The
resulting lens has a distance power and add power of 0.00 diopters and 2.00 diopters,
respectively, with 1.00 diopters of add power contributed by each surface. The
resulting channel power profile matches that required by the lens wearer of Example
1 and is depicted in FIG. 1. The channel length of the lens is 13.55 mm and the
location of the intermediate vision zone is 8.5 mm below the fitting point, consistent
with the pupil measurements of the wearer in Example 1.
Examples 3-4
Two lens wearers are measured using the procedure of Example 1 and their
pupil location measurements for intermediate and near tasks are found to be 9.5 mm
and 19 mm for the wearer of Example 3 and 10.5 and 21 mm for the wearer of

Example 4. Both require 0.00, 1.00, and 2.00 diopters power correction for distance,
intermediate and near vision, respectively.
Lenses according to the invention are made for the wearers. The convex
progressive surface of each lens has a distance zone curvature of 6.00 diopters and a
near vision zone curvature of 7.00 diopters. The channel power profiles of the
convex surfaces are shown in FIG. 2 as convex profile A and the channel lengths are
11 mm. The concave progressive surfaces have distance zone curvatures of 6.00
diopters and near zone curvatures of 5.00 diopters. The channel power profiles of the
concave surfaces are shown in FIG. 2 as concave profiles D and E, respectively, and
the channel lengths are 11 mm. The major reference point of each lens' concave
surface channel is displaced downward relative to the convex surface major reference
point by 4 mm and 6 mm for the lens of Examples 3 and 4, respectively. The
resulting channel power profiles of the lenses are shown in FIG. 1. The channel
lengths are 15 mm and 17 mm for Example 3 and Example 4, respectively, as
required by the pupil positions of the lenses' wearers for near viewing and the
locations of the intermediate zones are 9.5 mm and 10. 5mm, respectively, below the
fitting point
Examples 5-6
Two lens wearers are measured by the procedure of Example 1 and their
pupil location measurements for intermediate and near tasks are determined to be 5
mm and 15 mm below the fitting point for the wearer of Example 5 and 7.5 and 15
mm for the wearer of Example 6. Both wearers require 0.00 diopters, 1.00 diopters,
and 2.00 diopters power correction for distance, intermediate and near vision, but the
Example 5 wearer prefers a more rapid progression of power at the top of the channel
than does the Example 6 wearer.

FIG. 4 illustrates the lens channel profiles of the lenses made for these
wearers. The convex surface of each lens has a distance zone curvature of 6.00
diopters and near zone curvature of 7.00 diopters and is shown in FIG. 3 as convex
profile F. The channel length is 11 mm. The concave surfaces have distance
curvatures of 6.00 diopters and near zone curvature of 5.00 diopters. The channel
power profiles for the concave surfaces are shown in FIG. 3 as concave profiles G
and H, respectively. The channel length is 5.5 mm for both concave surfaces. The
optical center of the concave surface for Example 6 is coincident with that of the
convex surface. In Example 5, the optical center of the concave surface is displaced
4 mm downward from that of the convex surface. The resulting distance and add
powers for both lenses are 0.00 diopters and 2.00 diopters, with 1.00 diopters of add
power contributed by each surface. The channel power profiles of the lenses, shown
in FIG. 4, are matched to the pupil position and power progression preferences of
each wearer. Thus, although the channel lengths for the lenses are 11 mm, the
locations of the intermediate vision zones are 5 mm and 7.5 mm below the fitting
point.
Example 7
A lens wearer is measured using the procedure of Example 1 -and the pupil locations
measurements for intermediate and near tasks are determined to be 7 mm and 15.5
mm, receptively and the channel length is 15.5 mm - 4.00 ram = 11.5 mm. The
wearer requires 0.00, 1.00, and 2.00 diopters power correction for distance,
intermediate and near vision. The lens channel power profile suited to mis wearer is
shown in FIG. 5.
A lens is formed with a convex progressive surface and a concave regressive
surface. The convex surface has a distance zone curvature of 6.00 diopters and near
zone curvature of 9.00 diopters with a channel power profile shown in FIG. 6 as

convex profile I. The channel length is 14 mm. The concave surface has a distance
zone curvature of 6.00 diopters and near zone curvature of 7.00 diopters with a
channel power profile as shown in FIG. 6 as concave profile J. The channel length
is 13.5 mm. The concave surface optical center is displaced downward 2 mm relative
to that of the convex surface. The resulting distance and add powers of the lens are
0.00 and 2.00 diopters, respectively with 3.00 diopters of add contributed by the
convex surface and -1.00 diopters add contributed by the concave surface. The
resulting channel power profile is shown in FIG. 5. The channel length is 11.5 mm
and the location of the intermediate vision zone is mm below the fitting point meeting
the pupil measurements of the wearer.

WE CLAIM:
1. A spectacle lens comprising a first surface having a first channel and a
first channel power profile and a second surface having a second channel
and a second channel power profile, wherein the channel power profile of
the tens is the vector sum of the channel power profiles.
2. The lens as claimed in claim 1, wherein the first channel and the second
channel are aligned.
3. The lens as claimed in claim 1, wherein the first channel and the second
channel are displaced.
4. The lens as claimed in claim 1, wherein the first surface is a convex
progressive surface and the second surface is a concave progressive
surface.
5. The lens as claimed in claim 1, wherein the first and second channel
power profiles are substantially the same.
6. The lens as claimed in claim 1, wherein the first and second channel
power profiles are different.
7. The lens as claimed in claim 4, wherein the first and second channel
power profiles are substantially the same.
8. The lens as claimed in claim 7, wherein the first channel and the second
channel are displaced.
9. The lens as claimed in claim 8, wherein the displacement is about 0.1 mm
to about 20 mm.
10.A method for producing a spectacle lens comprising the steps of: a)
measuring a lens wearer's eye path and refractive power requirement
while the wearer is viewing an object at a distance, an intermediate, and a
near position; and b) providing a lens with a channel power profile based
on the lens wearer's eye path and refractive requirement.

11. The method as claimed in claim 10, wherein step b) is performed by
provided a tens comprising a first surface having a first channel and a first
channel power profile and a second surface having a second channel and
a second channel power profile, wherein the channel power profile of the
lens is the vector sum of the channel power profiles.
A spectacle tens comprising a first surface having a first channel and a first
channel power profile and a second surface having a second channel and a
second channel power profile, wherein the channel power profile of the lens is
the vector sum of the channel power profiles.

Documents:

IN-PCT-2000-513-KOL-FORM-27-1.pdf

IN-PCT-2000-513-KOL-FORM-27.pdf

in-pct-2000-513-kol-granted-abstract.pdf

in-pct-2000-513-kol-granted-assignment.pdf

in-pct-2000-513-kol-granted-claims.pdf

in-pct-2000-513-kol-granted-correspondence.pdf

in-pct-2000-513-kol-granted-description (complete).pdf

in-pct-2000-513-kol-granted-drawings.pdf

in-pct-2000-513-kol-granted-examination report.pdf

in-pct-2000-513-kol-granted-form 1.pdf

in-pct-2000-513-kol-granted-form 18.pdf

in-pct-2000-513-kol-granted-form 2.pdf

in-pct-2000-513-kol-granted-form 26.pdf

in-pct-2000-513-kol-granted-form 3.pdf

in-pct-2000-513-kol-granted-form 5.pdf

in-pct-2000-513-kol-granted-form 6.pdf

in-pct-2000-513-kol-granted-gpa.pdf

in-pct-2000-513-kol-granted-letter patent.pdf

in-pct-2000-513-kol-granted-reply to examination report.pdf

in-pct-2000-513-kol-granted-specification.pdf

in-pct-2000-513-kol-granted-translated copy of priority document.pdf


Patent Number 213784
Indian Patent Application Number IN/PCT/2000/513/KOL
PG Journal Number 03/2008
Publication Date 18-Jan-2008
Grant Date 16-Jan-2008
Date of Filing 14-Nov-2000
Name of Patentee ESSILOR INTERNATIONAL (COMPAGNIE GENERALE D'OPTIQUE)
Applicant Address 147 RUE DE PARIS, F-94220 CHARENTON-LE-PONT
Inventors:
# Inventor's Name Inventor's Address
1 MENEZES EDGAR 6558 HIDDEN WOODS ROAD, ROANOKE, VA 24018
PCT International Classification Number G02C 7/02
PCT International Application Number PCT/US00/03850
PCT International Filing date 2000-02-15
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 09/271,119 1999-03-17 U.S.A.